Various lancet assemblies or finger-pricking devices are commercially available to hospitals, clinics, doctors' offices, and the like, as well as to individual consumers. Such devices include a sharp-pointed member or a sharp-edged member, sometimes called a pricking member (such as a blade-like member or a needle-like member) that is used to make a quick puncture or incision of the patient's skin in order to provide a small outflow of blood. Various tests may be employed using only small amounts of blood so that blood flowing from such a wound or puncture is normally sufficient for these tests.
Such lancet assemblies are typically sterilized beforehand, and maintained in a sterile condition before use to ensure that the lancet is not contaminated by its surrounding environment. In addition, in order to prevent the lancet from wounding a user of the assembly or any other object around the user upon contact of the pricking member therewith during handing the assembly, the pricking member generally should not be physically exposed.
After using of the assembly, extra care must be taken by the user to avoid being punctured by a used lancet assembly. The risks in handling used lancets are greatly increased due to present day concerns regarding communicable diseases transmitted through body fluids such as blood (e.g. blood born diseases). Accordingly, the lancet assembly must be carefully handled until it can be properly disposed. Advances have been made in recent years to increase safety in handling such used devices. For example, pricking devices are currently available which include the features of automatic ejection and retraction of the blade edge tip, or a single shot firing mechanism.
One such lancet assembly, for example, is shown in Danish Design Patent No. MR 0933 (granted on Oct. 1, 1992). The Danish Design Patent lancet assembly is a self-contained device that includes a lancet structure, which includes a unitary ejector (projector or injector) and lancet element, used in combination with a holder (or a protective sheath or sleeve). The lancet structure is contained in the holder after use.
The Danish Design Patent lancet assembly is commercially available from Modulohm A/S (Denmark) under a trade name of Vitrex, of which structure is schematically shown in FIGS. 1 to 7, wherein
FIG. 1 shows a lancet assembly 10 before its use wherein a lancet structure 14 is incorporated into a holder 16;
FIG. 2 schematically shows a partial cross-sectional front view of the lancet assembly taken along line 2--2 in FIG. 1;
FIG. 3 schematically shows a cross-sectional front view which is similar to the view shown in FIG. 2 wherein the lancet structure 14 is disposed inside of the holder 16;
FIG. 4 schematically shows a cross-sectional front view which is similar to the view shown in FIG. 2 wherein the lancet structure 14 is being ejected for its use;
FIG. 5 schematically shows a cross-sectional front view which is similar to the view shown in FIG. 2 showing the lancet structure 14 and holder 16 after use;
FIG. 6 schematically shows an exploded perspective view of the lancet structure 14 of FIG. 1 before a blade 44 has been mounted; and
FIG. 7 schematically shows a perspective view of the lancet structure 14 after the blade 44 has been inserted.
The shown lancet assembly 10 essentially comprises a unitary lancet structure 14 and a holder 16. It is preferable that the lancet structure 14 of the lancet assembly 10, excluding the pricking member 44 (for example a blade member), be made of a polymer, such as a polyacetal (POM) resin, a polybutylene terephalate resin or a polyester copolymer resin for the member 14, and the holder 16 be made of an acrylonitrile-butadiene-styrene (ABS) resin, a polycarbonate resin or a polyester copolymer resin, each being injection molded as a unitary structure. During use, the members 14 and 16 move between the relative positions shown in FIGS. 2, 3, 4 and 5 sequentially.
The holder 16 includes a cavity 18 extending along an ejecting direction of the lancet structure 14 which cavity cooperates with an opening 20 for receiving the unitary lancet structure 14. Adjacent the opening 20 are outwardly extending flanges 21, as shown in FIG. 1, which are used to hold the holder 16 between the fingers of the user during operation of the lancet assembly 10. The cavity 18 includes guidance channels 80 on and along opposite sides of the inner wall of the cavity 18, which channels cooperate with mating protrusions 50 (such as pins) provided on a lancet body 46 of the lancet structure 14 so as to smoothly control movement of the lancet body 46 within the cavity 18. The opposite end of the holder 16 relative to the opening 20 is provided with an aperture 26 through which, during use of the assembly 10, a tip portion of the pricking member 44 protrudes and then retracts.
The holder 16 further includes channels or openings 30 along opposite sides, which open into the cavity 18 (and thus the channels pass through the walls of the holder). For further controlling movement of the unitary lancet structure 14 within the holder 16, arms 32 of the holder 16 disposed within the openings 30 include engaging protrusions (or extensions) 34, which extend into the cavity 18. The significance of these members will become clear upon a more detailed explanation of the unitary lancet structure 14.
The unitary lancet structure 14 comprises a lancet member 40 and an ejector 42. The lancet member 40 includes a pricking member (such as a blade or a needle) 44 and a lancet body 46 having cantilevered arms 48. To guide movement of the lancet member 40 through the holder 16, pins 50 are provided on the remaining opposite sides of the lancet body 46. As the lancet structure 14 is positioned within the holder 16 and actuated, the pins 50 cooperate with the guidance channels 80 provided on the inner walls of the cavity 18 to control the periscoping movement of the lancet member 40 along the channels 80 within the holder 16. The pricking element 44 of the lancet member 40, which is secured to and protrudes from one side of the lancet body 46, is formed from stainless steel or the like and includes a sharp point for piercing the patient's skin.
The ejector 42 includes a compressible spring member 54 and a U-shaped actuator 56. The U-shaped actuator 56 includes a base portion 58, to which the compressible spring member 54 is coupled, and upstanding actuator arms 60. The opposite end of the spring member 54 is attached to the lancet body 46. The lancet structure 14 is sized such that it may be disposed and move within the opening 20 and cavity 18 of the holder 16 in the positions shown in FIGS. 2 to 5.
To retain the lancet structure 14 in place within the opening 20 and the cavity 18 of the holder 16 prior to actuation of the lancet assembly 10, as shown in FIG. 2, outwardly extending lips (protrusions) 62 and 64 are provided along the outer surfaces of the actuator arms 60. In this position, the lips 62 are disposed within the channels 30 such that each of the lips 62 extends outward and seats against the upper edge of each channel 30. As a result, the lancet structure 14 cannot be pulled out of the holder 16 even though it is drawn along a direction opposite to the arrow A.
In the position shown in FIG. 2, the lips 64 are disposed adjacent the opening 20 of the holder 16. It may be noted that the outer surfaces of the lips 64 are tapered upwardly from the opening 20 so that the U-shaped actuator 56 easily slides into the holder 16 with cooperation of a tapered portion 20a (so called guiding portion) of the wall edge forming the opening 20 when the actuator 56 is depressed into the holder 16.
The lips 64 further function to lock the lancet structure 14 in position within the holder 16 after actuation (or use) of the assembly 10. Namely, as seen from FIG. 5 which shows a position after use, the lips 64 are disposed within the respective channels 30 such that they may abut against the upper edge of each channel 30 as a stop so as to prevent the members 14 and 16 from separating from each other (substantially the same position previously occupied by the lips 62 in the unactuated position of FIG. 3).
The actuator arms 60 function as an actuator for releasing (or ejecting) the lancet member 40 to permit the blade end 44 to protrude from the aperture 26, as will be apparent from the explanation set forth below. The end of each actuator arm 60 is provided with an inwardly tapered lip 68 along the inner surface of the arm 60, and an outwardly tapered lip 62 having an outside surface 70.
The operation of the lancet assembly 10 will be described with reference to FIGS. 2-5. Prior to actuation of the assembly, the members 14 and 16 of the assembly 10 are disposed in the relative positions shown in FIG. 2. To use the assembly, the user takes the holder 16 between his fingers and places the end of the holder 16 containing the aperture 26 against the skin of the patient. The user then uses his thumb to depress the U-shaped actuator 56 into the holder 16 along a direction of the arrow A, as shown in FIG. 2. As the actuator 56 is depressed, the engaging protrusions 34 of the holder 16 contact extensions 48a on the cantilevered arms 48 of the lancet member 40 so that the arms 48 cannot further proceed and the lancet member 40 is held in this initial position. As a result of the lancet member 40 being held in this position, the protrusions 34 compress and energize the spring member 54 as the user continues to depress the actuator 56.
As the user further continues to depress the actuator 56, the ends of the actuator arms 60 approach and contact or almost contact the engaging protrusions 34 and then separate (or release) the extensions 48a of the cantilevered arms 48 of the lancet member 40 from the engaging protrusions 34 of the holder 16, as shown in FIG. 3. As the engaging protrusions 34 and the arms 48 disengage from the abutting position thereof, the compressed spring member 54 is no longer restrained, and releases the accumulated energy to eject the lancet member 40 toward the aperture 26, as shown in FIG. 4. The compressed spring 54 extends such that the lancet member 40 moves to a position as shown in phantom in FIG. 4, so that the pricking member 44 protrudes from the aperture 26 to pierce the skin. After extension, the spring member 54 returns to its free-state position, as shown in solid lines in FIG. 5.
In the prior art lancet assembly using the blade as described above, the pricking member 44 is not shielded (or covered) and it is exposed. Namely, the blade edge 44 of the lancet structure 14 incorporated into the holder 16 is not covered at all and it is exposed within the holder 16. Therefore, each individual lancet assembly in the position as shown in FIG. 1 must be packed as a unit in a blister package or a resin made container, the whole of which has to then be sterilized. This type of packaging and sterilization is relatively expensive (the cost for the sterilization is proportional to a volume including the package).
As shown in FIG. 6, the lancet structure 14 is assembled by inserting the exposed blade 44 in the direction of the arrow. FIG. 7 shows the position of the blade 44 and lancet structure 14 after the insertion. In order to assemble the lancet assembly 10, the lancet structure 14 is inserted into the holder 16 while the blade 44 is exposed as in FIG. 7. Therefore, a step is required in which the blade 44 is exposed during handling (for example, a step in which the blade 44 is inserted to form the lancet structure 14 or a step in which the lancet structure 14 having the inserted blade 44 is inserted into the holder 16). In any such a step, since the blade 44 is exposed, its edge (or tip) is likely to contact another object so that the edge will very likely be damaged or otherwise injure the handling person. Further, the blade 44 is very likely to be contaminated with microorganisms such as a bacteria.